Testing out some video monitors to use for the 2 smaller video screens on the VK, the link to the video is below:
https://youtu.be/GZfk-dMUV5w
For my VK I'm looking at 2.5 inch diagonal screens with a 4:3 aspect ration, NTSC, and component video input.
The component input is not mandatory - I just want to be able to input video from an Arduino or Raspberry Pi board. It is possible that it may be easier to use 3 Raspberry Pi's (one for each video monitor) but that seems over kill since the 2 smaller monitors are monochrome and only the main one is color.
If I can find B&W CRT screens with a 2.5" diagonal I'd be all set but I haven't come across any yet._________________If only you could see the things I've seen with your eyes.

I've made a bit of progress on the graphics to the 2 small monitors, it's taking a bit of experimentation to format and send text, etc., to the screens through an Arduino micro-controller. Anyway, here's my results so far:
Left small monitor -

Still a few things to add to the display's, including animation and a feed of real time data.

Just want to say thanks to Joberg and Colin for feedback.

Colin, thanks for the reply on the extension rod – I have similar thinking on using “inch” sizes, my assumption was that what they had on hand in the early 80's in the US. I'm looking at some 3/8th inch aluminum rod and a matching black nylon bushing for my next tests of the VK arm._________________If only you could see the things I've seen with your eyes.

A little update on changes I made to the bar graph circuitry (to simplify building/fabrication).
https://youtu.be/SZJe4Y8weOs
I've been working on the timing for the bellows and think I pretty much have the movement down, I'll post up a video comparing the movement of the bellows in Leon's and Rachel's interview's and my bellows - all at 1/4th speed to make it easier to see._________________If only you could see the things I've seen with your eyes.

The adventure continues:
I finally started to really work on the “Eye” and the pieces surrounding it (my favorite part of this machine).. Wanting to get the raised portions around the “Eye” correct I looked closer at some pictures (including the newer ones from the PropStore) and came up with this:

The actual spaces may be a bit wider than 10 degrees but it seems to be a good place to start.

Looking back at actual dimensions for the “Eye” I finally decided to approach it a little differently (it is difficult to determine where the outer edge of the razor screen should be so instead I looked at the other dimension in the picture which I hope better matches the visible part of the razor screen.

The 0.775 in. dimension seems to match with the “B” dimension in the picture below.

Using this dimension the total diameter of the “Eye” would end up at 26.8mm with the raised portions around the border of the “Eye” being about 3.5mm wide (from inner to outer border). Of course this means re-scaling the EGB (Eye Gear Box) -arrgghh

Another area I'm working on is the Center of Rotation for the Voight Kampff “arm”.
Rest position:

End position:

My initial assumptions were that the center of rotation was either at the center of the servo that extended the arm or maybe at the lateral edge of the servo (closer to the outer edge of the VK) but due to looking closer at a few pictures I think it may be even further out than what I thought.

Stepper motor looks to be mounted against or close to inside wall of the machine, motor axle is very close to the angled rear part of the enclosure.

To the right (in the picture above) the lower pulley (at the end of the arm) the back plate seems to taper down and extend past the Servo motor to attach to the axle of the Stepper motor.

In no way is this a definitive assessment, I began with just trying to find where the rotation was occurring and it lead me down a rabbit hole to even more questions.

I'm currently trying to get some screen captures of the start and end of the arm raise to better calculate where the center of rotation is.

Please add your thoughts concerning these portions of the_________________If only you could see the things I've seen with your eyes.

One thin that I find interesting is that they allegedly built the VK machine in three days. And look who long it has taken today to figure out how to do it.

Tony

An excellent observation, Tony. It sort of puts things in perspective.

But then again, when they were building it they weren't constrained by having to make it accurate to something that already existed, all they were concerned with was getting it to work well enough to please Ridley and in time for the shoot, whatever it took.

What I would give to have been a fly on the wall during this process!

Steve_________________Politicians are like diapers.....they both need to be changed often, and for the same reason

You're right about the center of rotation! Tricky to say the least; I learned that by trial and error. The rod is actually off-center (more to the rear of the arm than in the middle. It's easy to make that mistake.

You have to count on the angle of the arm (so the top of the eye piece is parallel to the ground).
Then you have to be careful of the back of the arm (not to touch the side of the machine and impede the lift angle).

LBM, I’m at a similar stage to you working out the arm and mount. I’d noticed the angled plate also so I knew the centre of rotation was offset. I’d cross-referenced it with joberg’s build and indeed joberg had offset his.

Now I know nothing about electronics but I was looking at the NEMA stepper motors today. You said you had gone for the 17 but the 23 looks like it would do the job! In fact it fills out the space a bit more than the NEMA 17. The NEMA 24 looks even better as it seems to have a longer body! Having said this there seems to be many options for those motors which I don’t understand. So even thought I could pick a motor which looked visually close, it might not be fit for purpose.

With the motor in the photos being hard up against the side internal wall that really determines how much it’s offset by! (if you have the correct motor).

This was my thinking that the NEMA 17 may be too small!

Having said this you don’t see the motor so it doesn’t really matter what size it is, as long as it’s in the right position and lifts the arm without slipping.

I can understand your confusion Colin; those 2 pieces of plastic disappeared real fast when I tried to pivot the arm. Then, I put them back on, as to serve as stop pieces to keep the arm traveling to far up and keeping the top of the eye piece parallel to the ground.
After building a mock-up, I drilled directly into the base of the arm to put it in place.
Btw, the arm is actually a bit closer to the left-hand side of the machine.

Colin, your illustration is exactly what I was thinking, and what I'm currently testing out, I'll will post photo/video of my trials up ASAP. BTW I'm trying to build a mathematical model of the arm raise (based on photo's, screen captures) to figure out the center of rotation.
- I know this is a bit excessive but it is the type of mathematical (geometric/trigometric) that I like to try and figure out. Also, I know you are looking at stepper motors - a larger size than what I'm using is probably more accurate to the original build and the main rating you need to look at for stepper motor's (for this purpose) are torque values (how much it is able to move and how much it can keep stationary), the electronics for stepper motors are a lot simpler now (you can get drivers that do most of the work - I'll try and post some tutorials/links to make it easier)>_________________If only you could see the things I've seen with your eyes.